1. Field of the Invention
The present invention concerns an add-on module adapted to be mounted on a variable speed drive and comprising a casing which contains an electronic assembly and is provided at the rear with a connector which plugs into a corresponding connector on the variable speed drive.
2. Description of the Prior Art
Frequency converter type variable speed drives for controlling the speed of three-phase asynchronous motors essentially comprise a rectifier which supplies a DC voltage to a smoothing filter capacitor (AC-DC converter) and a power transistor inverter (DC-AC converter) energized by the filtered DC voltage.
The variable speed drive provides the most commonly required functions. It can be configured to suit more complex applications by means of add-on options such as:
an operator dialog add-on to display parameters and faults and the configuration of functions; PA1 an IBM PC or compatible microcomputer connection add-on for downloading and logging settings; PA1 an add-on to provide a serial link to an automatic programmable controller bus.
These add-on modules are in the form of a casing containing the electronics and provided at the rear with a connector adapted to be plugged into a connector at the front of the variable speed drive.
An object of the invention is to provide an L-shape add-on module for variable speed drives so that the overall size is minimized. This L-shape facilitates adding a memory card to the module.